At present, in a distributed antenna system that is separated geographically, low-power RRHs (Remote Radio Head, remote radio head) are all distributed in coverage of a macro cell, where each RRH connects to an eNB (Evolved Node B, evolved base station) through a fiber, and a macro base station directly connects to the eNB. The RRHs or the macro base station sends data to a UE (User Equipment, user equipment) through respective TPs (Transmission Point, transmission point/transmission point), and in an existing CoMP (Coordinated Multi-Point operation, coordinated multi-point transmission) system, the data can be sent to the UE through multiple TPs.
Here, the two TPs jointly sending data to a UE is used as an example for description: The eNB notifies the UE of two CSI RS (Channel State Information Reference Signal, channel state information reference signal) configurations, where the CSI RS configurations correspond to the two TPs. For example, the two CSI RS configurations, namely, CSI RS Config.0 and CSI RS Config.1, correspond to the macro base station and RRH1, respectively; then, the UE measures CSI (Channel State Information, channel state information) according to the two received CSI RS configurations and feeds back the measured CSI to the eNB, where the CSI includes an RI (Rank Indicator, rank indicator) and/or a PMI (Precoding Matrix Indicator, precoding matrix indicator) and/or a CQI (Channel Quality Indicator, channel quality indicator) and phase adjustment information between two CSI RSs, and the phase adjustment information carries a phase adjustment factor ejθ. For example, a PMI corresponding to CSI RS Config.0 and that corresponding to CSI RS Config.1 are PMI0 and PMI1, respectively, it is assumed that PMI0 and PMI1 indicate precoding matrices V0 and V1, respectively, and in this case, after phase adjustment, an obtained precoding matrix is V=[V0, ejθV1]T; after receiving the CSI fed back by the UE, the eNB may perform data transmission based on the received CSI, for example, data after precoding is VS, where S is a vector formed by a modulation symbol to be sent; the UE receives a signal y sent by the eNB and detects transmitted data according to y, where y=HVS+n, H=[H0 H1], H0 and H1 are channel matrices from the UE to the two TPs, and n is received noise and interference; and in this way, transmitted data S can be obtained according to y.
However, the UE receives signals transmitted by geographically separated TPs and then received power from TPs is different. The precoding matrix obtained according to the prior art does not apply to a channel matrix with power imbalance and therefore interference cannot be effectively canceled or suppressed, thereby resulting in degradation in system throughput.